The present invention relates to a thin sheet punching device for obtaining a plurality of small pieces of similar shape corresponding to the punching hole of a press punching die, by processing a thin sheet of raw material of relatively large size by means of punching tools of a punch press machine.
Conventionally, the metal outer jacket of a battery is fabricated by the steps illustrated in FIGS. 20A-20F. Firstly, as shown in FIG. 20A, a hoop material made from tinplate steel sheet and having a thickness of approximately 0.2 mm is cut to prescribed dimensions to obtain a square-shaped raw material sheet 1 having a relatively large size, for example, 785 mmxc3x97850 mm. Thereupon, as shown in FIG. 20B, slits parallel to the edges are formed in the side edge regions, each approximately 2 mm from two mutually opposing side edges of the raw material sheet 1. These two side regions 2 are removed, whereupon slits are formed at prescribed intervals between the two end edges of the sheet, as illustrated by the double-dotted lines. Thereupon, as illustrated in FIG. 20C, the raw material sheet 1 is divided into a prescribed number of strip-shaped intermediate sheets 3. These intermediate sheets 3 are then respectively punch processed using prescribed press punching tools, as shown in FIG. 20D, thereby yielding a plurality of jacket blank sheets 4 like that shown in FIG. 20E.
The aforementioned jacket blank 4 is then bent into a cylindrical shape, as shown in FIG. 20F, the opposing side edges 4a, 4b thereof are butted against each other, and a base section 5 is formed by curl caulking the edge region of the lower side 4c towards the inside, thereby forming an outer jacket for a battery 7 approximately having a bottomed cylinder shape. The reason that the aforementioned raw material sheet 1 is divided into a plurality of intermediate sheets 3 by means of a slitter is because, in order to achieve mass production jacket blanks 4 having small cutaways 6a, 6b respectively at the four corners thereof, in such a manner that there is no variation in the shape of the aforementioned cutaways 6a, 6b, it is difficult to adopt any means other than punch pressing wherein a plurality of jacket blanks 4 are punched out simultaneously from an intermediate sheet 3.
However, in the method for manufacturing the aforementioned outer jacket 7 for a battery, as FIG. 20D clearly demonstrates, a very large amount of raw material waste is left after the strip-shaped intermediate sheets 3 have been punch pressed, and hence material loss is high. Accordingly, the number of jacket blank sheets 4 obtained from a single intermediate sheet 3 is reduced, and therefore productivity is low. Production numbers for small-scale batteries have been extremely high in recent years, and therefore the material loss described above leads to enormous economic losses, and is also undesirable from the viewpoint of preserving resources.
In order to resolve problems such as the foregoing, the applicants of the present invention have proposed a method for manufacturing metal outer jackets for batteries by means of the processes described below (see International Laid-Open Patent No. WO99/12218). FIGS. 21A-21F illustrate the sequence of manufacturing steps. Firstly, a hoop material made from tinplate steel sheet of approximately 0.2 mm thickness is cut to prescribed dimensions, to obtain a square-shaped raw material sheet 1 similar to that illustrated in FIG. 20A. Slits are then formed in this raw material sheet 1 running along the cutting lines indicated by the parallel double-dotted lines in the diagram, thereby dividing the raw material sheet 1 into two edge sections 8 of approximately 2 mm width from opposing ends of the sheet 1, and a prescribed number of strip-shaped first intermediate sheets 9 cut in parallel with these edge sections 8.
Thereupon, as shown in FIG. 21C, the two edge regions of each first intermediate sheet 9 in the longitudinal direction thereof are removed by forming further slits, and a plurality of rectangular second intermediate sheets 10 are obtained by forming slits along a plurality of parallel cutting lines running perpendicularly to the longitudinal direction of the first intermediate sheet 9. The longitudinal dimension of these second intermediate sheets 10 is set approximately 1 mm longer than the length of two jacket blanks 11, which are the objects to be fabricated, laid end to end. Moreover, as shown in FIG. 21D, the central portion of each of the aforementioned second intermediate sheets 10 in the longitudinal direction thereof is then cut perpendicularly to said longitudinal direction by a press cutting tool 12 having an approximately I-shaped cross-section, thereby dividing it into two jacket blank sheets 11, as illustrated in FIG. 21E. These jacket blanks 11 are formed with two cutaways 13a, 13b on the upper and lower ends of one side edge 11a only, these cutaways 13a, 13b having a width respectively twice the size of the two cutaways 6a, 6b formed at the four corners of the jacket blanks 4 in FIG. 20E. The jacket blank 11 is then bent into a cylindrical shape, as shown in FIG. 21F, the two side edges 11a, 11b thereof being butted against each other, and the edge region of the lower side 11c thereof is then curl caulked towards the inside, thereby yielding an outer jacket for a battery approximately having a bottomed cylinder shape.
In the manufacturing method for an outer jacket 14 described above, instead of means for obtaining jacket blanks 4 by press punching a strip-shaped intermediate sheet 3 as illustrated in FIGS. 20A-20F, jacket blanks 11 are obtained by respectively press cutting second intermediate sheets 10 formed by dividing a strip-shaped first intermediate strip 9 into a plurality of sheets. Compared to the method for manufacturing the outer jacket 7 in FIGS. 20A-20F, the raw material remainder created after forming the jacket blanks 11 is significantly reduced to approximately xc2xc. Since the number of jacket blanks 11 that can be obtained from the same raw material sheet 1 increases in accordance with the decrease in raw material remainder, it is possible to obtain an excellent merit in that the material yield rate increases dramatically.
However, whilst the method for manufacturing an outer jacket 14 described above brings the aforementioned excellent merit, it stills leaves scope for further improvement. Specifically, the method for manufacturing an outer jacket 14 described above comprises a cutting step performed by a slitter device on a raw material sheet 1, a cutting step performed by a slitter on respective first intermediate sheets 9, and a press cutting step performed by a press tool 12 on respective second intermediate sheets 10, and therefore, since the number of manufacturing steps is relatively large in this way, a problem exists in that further improvements in productivity cannot be achieved.
Furthermore, although the material waste created after forming the jacket blanks 11 is reduced significantly in comparison with the method for manufacturing an outer jacket 7 illustrated in FIGS. 20A-20F, it cannot be regarded as being sufficiently reduced. In other words, the press tool 12 for dividing the second intermediate sheets 10 into two jacket blanks 11 by press cutting comprises a slit-forming cutting section 12a for forming the cutting line portion, as illustrated in FIG. 21D, and approximately triangular cutaway-forming cutting sections 12b, 12c provided at either end portion of this slit-forming cutting section 12a, but in order that the second intermediate sheets 10 are press cut smoothly to obtain jacket blanks 11 of the correct shape, it is necessary to set the width of the slit-forming cutting section 12a to approximately 1 mm at the minimum. Moreover, it is also necessary to set the cutaway-forming cutting sections 12b, 12c to a dimension equalling double the length of the cutaway widths of the cutaways 13a, 13b to be formed, plus the 1 mm width of the slit-forming cutting section 12a. Therefore, a considerable amount of material waste is created after press cutting of the second intermediate sheets 10. This production of material waste leads to relatively large economic losses, since the number of small-scale batteries currently being produced is very high indeed.
Besides the method for manufacturing an outer jacket described above, there has also been proposed means for obtaining a large number of small pieces, such as the aforementioned jacket blanks, by punch processing of works, such as a thin raw material sheet of relatively large size (see, for example, Japanese Patent Publication No.(Hei)7-73765 and Japanese Patent Application Laid-open No.(Hei) 1-130825). The device disclosed in Japanese Patent Publication No.(Hei)7-73765 is provided with an X-Y table having a composition which integrates a carriage base, a front side table, and a transport table. A work held by a clamper in this X-Y table is moved in the directions of the X axis and Y axis by means of the X-Y table, prescribed locations which are to be punched out being registered in position between a punch and a die, whereupon punch processing is performed, and small pieces being cut out by combined operation of a punch and die in a cutting out section located to the side of the punch processing section. In the device disclosed in Japanese Patent Application Laid-open No.(Hei) 1-130825, on the other hand, a work on a table is held and fixed in a prescribed position by two work holders, and a punching tool is registered in position by moving in the X axis and Y axis directions, whereupon punch processing is performed on the work.
Conventional devices for punch processing of works are composed in such a manner that either a work is registered in position by controlling the movement of an X-Y table, or a punching tool is registered in position corresponding to a punching location on a work, by moving the tool respectively in the X axis and Y axis directions. Therefore, although it is possible to cut out jacket blanks of small size having cutaways as described above, from a thin raw material sheet of relatively large size, whilst controlling the shape thereof accurately, it is not possible to punch out such blanks at a good productivity rate, whilst reducing the material waste as far as possible.
The present invention was devised in view of the foregoing problems in the prior art, an object thereof being to provide a thin sheet punching device which is capable of performing punch processing with good productivity by means of simplified manufacturing steps, whilst reducing material waste to a minimum, when obtaining a plurality of small pieces forming blanks for the outer jackets of batteries, for example, from a thin raw material sheet of relatively large size.
In order to achieve the aforementioned object, the thin sheet punching device according to the present invention comprises the following elements. A thin sheet transporting mechanism transports rectangular large thin sheets of prescribed dimensions, one at a time, and loads same onto a material supply/position registering area. A thin sheet positioning mechanism registers the large thin sheet on the material supply/position registering area by moving same linearly by pressing two adjacent edges thereof in mutually perpendicular directions by means of a pair of pushers, whilst pressing the two opposing edges of the large thin sheet against a pair of reference position stopper members. After the rear edge portion of the large thin sheet in a registered state has been gripped by a plurality of chuck tools and the registration of the large thin sheet by the thin sheet positioning mechanism has been released, a thin sheet movement control mechanism transports the large thin sheet in an X direction to a control start position. Thereupon, it alternately performs Y direction movement control for moving the sheet reciprocally by a prescribed movement pitch in a Y direction which is perpendicular to the X direction, and X direction movement control for moving the sheet by a prescribed movement pitch in the X direction each time it has been moved in either Y direction, thereby controlling the movement of said large thin sheet in such a manner that a plurality of alternate punching locations of a plurality of punching locations set in a row in the Y direction of the large thin sheet are successively registered in processing positions. A punch press machine provided with a plurality of press punching tools, each comprising a die and a punch, aligned in the Y direction at the processing position, is driven each time the thin sheet movement control mechanism performs movement control in either the X direction or the Y direction, thereby simultaneously punching out the plurality of alternate punching locations in the Y direction of the large thin sheet.
In this thin sheet punching device, in contrast to a conventional method, it is not necessary to provide cutting steps performed by a slitter. Small pieces for forming blanks for the outer jackets of batteries can be obtained simply by performing a continuous series of punching steps, wherein a large thin sheet is gripped by chuck tools, and moved and controlled alternately in the X direction and the Y direction, whereby a plurality of punching locations are simultaneously positioned at respective punching tools of a punch press machine and then punched out. The manufacturing process is thus remarkably simplified. Moreover, since a plurality of small pieces can be punched out simultaneously by a single operation of the punch press machine, productivity is dramatically improved.
Since the chuck tools grip the large thin sheet when it is in a registered position, they are capable of gripping the large thin sheet accurately in prescribed positions. Furthermore, since a plurality of alternate punching locations in a single row of aligned punching locations on the large thin sheet are punched out simultaneously, the punch margin in the large thin sheet, which is pressed by the stripper of the punch press machine, is only subjected to a pulling force in one direction, despite the fact that a plurality of small pieces are being punched out simultaneously. Therefore, the punch margin can be set to a small width, and the material waste remaining after the punching of the large thin sheet has been completed is significantly reduced in comparison to a conventional method. In particular, when obtaining small pieces forming blanks for the outer jackets of batteries, a very great economic advantage is obtained by significantly reducing material wastage, since the current production numbers for small-scale batteries are extremely high.
The plurality of chuck tools in the aforementioned invention each comprise a fixed jaw section formed with an engaging projection protruding from the chuck surface, and a movable jaw section having a sharp toothed section formed at the front end portion of a cylindrical shape capable of containing the engaging projection therein. The movable jaw section is provided in such a manner that it can be moved reciprocally with respect to the fixed jaw section, and the chuck tools are constituted in such a manner that a portion of the large thin sheet inserted between the jaw sections is caused to undergo plastic deformation into a shape corresponding to that of the engaging projection by means of pressure imparted by the toothed section, whilst the region surrounding this deformed portion is held between the toothed section and the chuck surface.
Although the large thin sheet is of relatively large size and heavy weight, the chuck tools grip it in a securely held state which does not allow the sheet to deviate from its gripping position, even when the large thin sheet is moved and controlled at high speed. Therefore, in accordance with the precisely controlled movement of the chuck tools, it is possible to register the large thin sheet in position extremely accurately with respect to the punching tools of the punch press machine, and therefore the width of the punch margin can be reduced.
In the thin sheet punching device comprising the aforementioned chuck tools, desirably, the thin sheet movement control mechanism comprises a program-controlled X direction movement control servo motor and Y direction movement control servo motor.
Since the servo motors can be rotated and controlled with high precision by program control implemented by a controller, a thin sheet movement control mechanism mounted with these servo motors is able to control the movement of the chuck tools gripping the large thin sheet by extremely accurate movement pitches in the X direction and Y direction, respectively, in contrast to cases where the large thin sheet is moved and controlled by operating the chuck tools or an X-Y table, or the like, by means of an air cylinder, or other such driving means. Therefore, in addition to the chuck tools gripping the large thin sheet in a very secure manner, it is also possible to register the large thin sheet in position with great accuracy, with respect to the punching tools of the punch press machine. Therefore, it is possible to punch out along the outer shape of the print patterns, that have previously been formed at punching locations on the large thin sheet, with good accuracy. Moreover, since the chuck tools grip the large thin sheet when it has been registered accurately by means of the thin sheet positioning mechanism, it is not necessary to provide gripping reference holes, or the like, for the large thin sheet.
In a thin sheet punching device provided with the aforementioned chuck tools and thin sheet movement control mechanism, a punch margin having a width of 1.0 mm-0.4 mm is set respectively between each pair of adjacent punching locations on the large thin sheet.
Since the large thin sheet can be gripped very securely by the chuck tools and these chuck tools can be moved and controlled with high precision in the X direction and Y direction by the servo motors, thereby registering them accurately in position, it is possible to set the smallest possible width for the punch margin, and hence the material waste after punching of the large thin sheet is greatly reduced and the material yield rate is dramatically improved.
In the inventions described above, desirably, the thin sheet punching device further comprises a thin sheet setting table on which a plurality of large thin sheets are loaded in a stacked fashion. The thin sheet transporting mechanism is provided with a plurality of suction cups for successively picking up only the uppermost sheet of the plurality of large thin sheets on the thin sheet setting table, and for transporting same to a material supply/position registering area. Meanwhile, the punch press machine is engaged in punch processing a large thin sheet. The thin sheet setting table comprises a plurality of free-moving balls provided in a rotatable fashion, and a thin sheet receiving plate provided movably on the free-moving balls, which moves reciprocally between a large thin sheet setting position and a suction position confronting the thin sheet transporting mechanism.
Although the total weight of a plurality of stacked large thin sheets is relatively heavy, since the thin sheet receiving plate onto which these large thin sheets have been loaded moves extremely smoothly by means of the rotation of the free-moving balls, it is possible for the sheets to be registered accurately in a suction position confronting the thin sheet transporting mechanism simply by being pushed lightly by an operator, for example. Moreover, since the large thin sheets are positioned accurately by means of the thin sheet positioning mechanism when they are transported to the material supply/position registering area by the thin sheet transporting mechanism, it is simply necessary from them to make contact with the thin sheet transporting mechanism. Consequently, in this thin sheet punching device, the operation of setting a plurality of large thin sheets in a stacked state can be achieved very readily and swiftly, by means of a simple structure.
In the aforementioned inventions, the first reference position stopper member for restricting the position of the rear edge of a large thin sheet opposing the thin sheet movement control mechanism comprises the following elements. A position restricting face thereof confronts the rear edge of the large thin sheet when the member has been raised from a retracted position to an upper registration reference position. A guide face thereof, formed on the opposite side to the position restricting face, slides against material waste generated after the large thin sheet has been punch processed as the large thin sheet is moved in the X direction by the thin sheet movement control mechanism, thereby guiding same into a waste recovery area. Moreover, desirably, the first reference position stopper member is composed in such a manner that it is located in the registration reference position when the large thin sheet is being registered in the material supply/position registering area, and when the large thin sheet is being punch processed by the punch press machine.
By adopting this composition, it is possible to invest the first reference position stopper member with the dual functions of restricting the position of the large thin sheet and guiding the material waste into the waste recovery area. Therefore, when the first reference position stopper members are located in the registration reference position, at the same time that the material waste is guided into the waste recovery area by the guide face whilst the large thin sheet is punch processed by the punch press machine, a large thin sheet can also be transported to the material supply/position registering area by the thin sheet transporting mechanism, and that large thin sheet can be registered in position. Therefore, immediately after punch processing has been completed, this registered large thin sheet can be gripped by the chuck tools and transported to the control start position, thereby further enhancing the efficiency of the punching steps for the large thin sheets.
In the aforementioned inventions, each of the plurality of dies in the punch press machine has a similar shape wherein a punching hole having a shape corresponding to the small pieces to be punched out is formed in the central region thereof and an L-shaped cutaway step section and a linear-shaped cutaway step section are formed respectively on either side of the punching hole. The dies are each affixed to a die holder in the same installation configuration, and escape grooves permitting the chuck tools to move by a prescribed movement pitch in the Y direction at the final punching position of the large thin sheet and transit grooves permitting the chuck tools to pass by in the X direction are constituted by integrating the L-shaped cutaway step section of one die with the linear-shaped cutaway section of the other die in each pair of adjacent dies respectively opposing the positions of the chuck tools, in such a manner that they are mutually connecting.
Since the chuck tools can enter into the escape grooves formed between two adjacent dies when they advance to the final punching position of the large thin sheet, it is possible to reduce the width of the clamping margin on the large thin sheet where it is gripped by the chuck tools, by a corresponding amount, and hence the amount of waste material remaining after the large thin sheet has been punch processed can be further reduced. Moreover, by forming all the dies with the same shape, it becomes unnecessary to prepare a large number of spare parts, and hence management of components is facilitated. Furthermore, since the dies are all the same shape and are interchangeable, when they are all removed as a block for regrinding and then reinstalled, it is not necessary to specify the installation position for each die. Therefore, installation of the dies can be performed readily and swiftly, and maintenance characteristics are dramatically improved.
Desirably, the thin sheet movement control mechanism in the aforementioned inventions performs movement control of the large thin sheets in the following manner. Firstly, when a large thin sheet in a registered state in the material supply/position registering area is transported in the X direction whilst being gripped by the chuck tools, the large thin sheet is halted in a control start position wherein alternate punching locations in the first row in the Y direction of the large thin sheet are registered in positions opposing punching tools. The large thin sheet is then moved and controlled in the Y direction and X direction from the control start position until a final punching position where the chuck tools enter inside the escape grooves of the dies. When the chuck tools are advanced to a release position having passed fully through the transit grooves of the dies, the material waste generated when punching of the large thin sheet has been completed is released by opening the chuck tools, whereupon the chuck tools advance further from the release position to a gripping position, where a large thin sheet registered in position on the material supply/position registering area is gripped by the chuck tools.
Since the chuck tools are controlled in such a manner that they do not make any unnecessary movements in the X direction, it is possible further to enhance the efficiency of the large thin sheet punching steps.
In the aforementioned inventions, desirably, the thin sheet punching device further comprises a small piece transporting and aligning mechanism for transporting small pieces punched out from a large thin sheet by the punch press machine and stacking same in an aligned state. The small piece transporting and aligning mechanism comprises the following elements: An output magnetic conveyor outputs small pieces which drop down after being punched out by the punch press machine, to the exterior of the punch press machine, whilst maintaining the positions thereof after punching. A stacking magnetic conveyor guides small pieces discharged from the end of the path of the magnetic conveyor in an upward vertical direction and then transports same in a downward vertical direction, the small pieces being held magnetically in a virtually perpendicular position with respect to the surface of the conveyor. A small piece receiving plate is positioned in the vicinity of the magnetic conveyor, and acts to prevent the conveyance of the small pieces and to stack them on each other. A small piece expelling member expels a prescribed number of small pieces stacked up on the small piece receiving plate, to the exterior of the small piece receiving plate.
By adopting this composition, small pieces produced by punch processing of a large thin sheet can be obtained in an aligned, stacked and correctly orientated state, in a number corresponding to a single large thin sheet, thereby greatly facilitating the processing steps in subsequent stages.
An intermediate magnetic conveyor can be positioned between the output magnetic conveyor and the stacking magnetic conveyor in the small piece transporting and aligning mechanism. This intermediate magnetic conveyor is inclined to a prescribed angle with respect to the horizontal plane, in a perpendicular direction to the direction of transport, and a pair of guide sections are provided on either side of the stacking magnetic conveyor, an interval smaller than the width of the small pieces in the perpendicular direction to their direction of transport being allowed between the guide sections.
Thereby, when the small pieces held magnetically onto the stacking magnetic conveyor at a virtually perpendicular position thereto are guided in an upward vertical direction and then a downward vertical direction, they are prevented from falling downwards because they confront the guide sections which are separated by an interval narrower than the width of the small pieces, and hence the small pieces are conveyed whilst maintaining a virtually perpendicular position with respect to the stacking magnetic conveyor. Consequently, the small pieces transported by the stacking magnetic conveyor are stacked accurately in an aligned and orderly state on the small-piece receiving plate.